When the United States entered World War I, the Allies viewed America as the world’s leading industrial power and a vast source of fresh manpower. Much of the U.S. contribution to the naval side of the conflict would be in line with the first view, of the United States as the home of mass production. The best-known examples are the floods of merchant ships, intended to make up for losses to U-boats, and of destroyers and subchasers.
Less well known was an imaginative U.S. naval initiative to produce and lay a mine barrier to close off U-boat routes out of the North Sea. The British were already blocking the Strait of Dover with mines and patrol ships. To get at merchant ships approaching western British ports from North America, U-boats had to cross the North Sea and make their way around Scotland. Similarly, U-cruisers had to take this route to reach America’s East Coast, where they attacked in 1918.